In 2010 Chicago’s venerable Delmark Records purchased the avant-garde catalog of the moribund Canadian jazz imprint Sackville Records, which was formed in 1968 by Bill Smith and John Norris. In general, the former, who also edited and published the jazz magazine Coda, was responsible for the label’s free-jazz offerings, while the latter focused on more traditional sounds. Delmark ended up buying that part of the catalog last year. By 2011 Delmark was distributing the remaining Sackville avant-garde catalog, promising to eventually issue previously unreleased material. That promise came true last month when Delmark released Live at “A Space” 1975, a fantastic live recording by the Roscoe Mitchell Quartet. That title has been previously issued both on vinyl and CD, but the new Delmark release adds on four previously unreleased tracks from that concert, adding another 20 or so minutes to the album.